New PHP and have this error - The preview could not load due to the iframe response being incomplete

The preview could not load due to the iframe response being incomplete. This is most often related to a plugin conflict, or customizations introducing a PHP error.

Origin URL:

Preview URL:

Hi @TSICentral,

Please check under Settings > General and make sure the urls are using https instead of http

If that doesn’t help, you can try other solutions listed below


Hi, thank you the URL is https, stiil the same… Thanks

Hi @TSICentral,

I was unable to login to your WordPress dashboard. When I visit the login URL, it always redirects me to home page URL. Could you please double check?

Please also follow up the steps below:

  1. Test for a plugin conflict. You can do this by deactivating all third-party plugins, and see if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
  2. Switch to the parent theme to check if the issue persists.
  3. Increase the PHP Memory Limit of your server. Click here for more detailed information and how to increase the PHP memory limit.

Let us know how it goes!


I disabled all the plugin’s and found that G-Zip & UberMenu are the problems, Can’t solve the UBERMENU one. The PHP checker keeps hanging with this error "Error: Internal Server error Status 500".

UberMenu keeps asking for "UberMenu update check error: Please provide Username and Purchase Code in the Control Panel > Updates tab." I have updated it but same error.

Thank you

Hi @TSICentral,

Have you tried increasing the memory limit as suggested after the plugin conflict test? Due to multiple features from different plugins, the presence of one may cause this issue like Ubermenu if your memory limit is too low. But I coldn’t confirm any of this as any of the login URL isn’t working.

Please provide the correct login URL and increase the memory limit. You can also try upgrading your PHP version to 5.6 or above, 7.0+ is more recommended and in case it’s still old. Just in case it uses some features not available from older PHP versions.


Hi, now I am getting a Plugin could not be activated because it triggered a fatal error.
Fatal error: Cannot declare class Cornerstone_Plugin_Base, because the name is already in use in /home/stationco/public_html/wp-content/plugins/cornerstone/includes/utility/plugin-base.php on line 6

I have tried to install Cornerstone again as per the forum but still can’t activate it.

Hi @TSICentral,

Please don’t activate Cornerstone since you’re already using the Pro theme. Pro theme has its built-in, and cornerstone is only applicable for X theme. You’re free to delete cornerstone :slight_smile:



This is what happens when I try go onto content
Not Found
The requested URL /pro/ was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Hi @TSICentral,

I reset your permalinks by going to Settings > Permalinks then click on Save Changes

That seems to have fixed the issue.

Kindly check n your end.


Thank you so much!!

You are most welcome.

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